1. Field of the Invention
The present invention relates to a metal-ceramic composite substrate and, more particularly, relates to an improvement of a metal-ceramic composite substrate wherein heat generated in a semiconductor element can be dissipated therefrom efficiently.
2. Description of the Prior Art
Several methods are known in the art of joining metal members to ceramic members.
A typical example is the direct joining method in which the metal member is directly joined to the ceramic member.
Another example is the intermediate material method in which the metal member is joined to the ceramic member by inserting an intermediate material therebetween.
In the direct joining method, a copper plate is directly joined to an alumina substrate in the atmosphere of inert gas and heated and cooled is described, e.g., in U.S. Pat. No. 4,811,893 etc.
As the intermediate material method, an active metal method and a metalizing method are known.
In the active metal method, an intermediate material containing an element of fourth group of the periodic table, such as Ti or Zr etc., or an alloy containing said element is inserted between the metal member and the ceramic member.
For example, in the case that the stainless steel and the silicon nitride are joined, Ag--Cu--Ti base alloy is used as the intermediate material, and in the case that the copper and the alumina are joined, Cu--Ti base alloy is used as the intermediate material.
Recently, however, it is required to use semiconductor elements of a high electrical power and high integration to be mounted in the electronic equipment including the semiconductor device according to the miniaturization of said electronic equipment, and thus the heat quantity generated in the energized semiconductor elements becomes large.